Two men toting a briefcase stuffed with false bond certificates purportedly worth trillions of dollars tried to bluff their way into the exclusive Vatican bank in a foiled fraud plot, Italian police said Sunday.

Financial Guard police Lt. Col. Davide Cardia said the would-be swindlers, who were wearing business suits, tried to convince Swiss Guards at a Vatican City gate earlier this month that “cardinals were expecting them.”

Cardia told The Associated Press in a phone interview that the suspects, a middle-aged Dutchman and a U.S. citizen, were detained by Vatican authorities after rapid checks by Vatican officials showed they had no such appointment nor connections with the Institute for Religious Works, the formal name of the bank, which is behind the tiny city-state’s walls and isn’t open to the public.

The Vatican has been scrambling to upgrade procedures and standards at the bank since a 2010 money-laundering probe.

Cardia said the fake documents purported to be bond certificates for non-Italian companies. “The sum — worth some 3 trillion euros (more than $4 trillion) — is impressive, even though it’s only symbolic because we’re talking about false” certificates, said Cardia, in charge of the financial police’s operations in Rome and surrounding area.

Investigators suspect the men might have planned to use the fake bonds as security to open a hefty line of credit through the Vatican bank.

The Vatican asked Italian authorities to help in the investigation.

Italian police searched the men’s room at a hotel near the Vatican and seized stamps and seals used to create the false documents, Cardia said.

Both suspects, whose names weren’t released by police, had been previously investigated for attempted fraud in Asian countries, Cardia said without elaborating. They were issued citations and released on their own recognizance pending further investigation, since Italian law doesn’t require arrest for investigation of attempted fraud, according to the official. Both are believed to have left Italy.